University of Houston archaeologist Randolph Widmer obtained 18 radiocarbon dates from clam shells recovered from various contexts in the 2000 field school excavations at the Miami Circle. Many of these shell samples were removed from cut hole features. Widmer combined these with earlier radiocarbon dates and proposed five prehistoric chronological phases for the site. The dates confirm that the site deposits are primarily from around 750 B.C. to A.D. 550, called by archaeologists the Glades I early period. The major break in dates comes between Widmer’s Phases IV and V, with the last phase representing a much later occupation around A.D. 1330-1680.